Image courtesy of Citizens for NSRL via Congressman Seth Moulton

Connecting North Station and South Station by rail could unlock $30 billion in economic benefits, far more than the major infrastructure costs the project would require, according to a new study commissioned by a congressman who supports the idea.

Congressman Seth Moulton touted a new analysis Monday from the Harvard Kennedy School, which said that linking the rail hubs would make a greater difference on transportation connectivity, housing affordability and emissions reductions than expanding South Station.

Moulton said the study, for which a detailed white paper will be published later in the summer, found the rail link could carry $28 billion to $31 billion in combined benefits at a cost of $7.9 billion.

“Expanding South Station – the state’s current plan – would waste $4 billion in taxpayer money and barely last two decades, while creating no improvements in frequency or service anywhere else on the system,” Moulton wrote in a summary of the report. “It would do nothing to alleviate our horrific traffic or dire housing shortage across the state, And rather than a new climate-resilient environmental justice neighborhood connecting Dorchester and South Boston, it would use that land for a rail yard that’s submerged every time we have a major storm.”

A North-South Rail Link, Moulton added, “is the single most important project for transportation in Massachusetts.”

Administration officials are reportedly considering an overhaul to add more tracks to South Station. A passenger rail expansion to the South Coast is set to open next year after another delay, and early steps are underway for another expansion to western Massachusetts.

However, commuters who want to cross Boston still face disrupted travel. To get from Moulton’s hometown of Salem to Foxborough via train, a rider would need to take the commuter rail to North Station, get on the MBTA’s Green Line, switch to the Red Line, then get on another commuter rail train at South Station.